Back adjustment for office chairs



1958 H. w. PARROTT ET AL 2,863,497

BACK ADJUSTMENT FOR OFFICE CHAIRS Filed March 5, 1957 3 Sheets-Sheet 1V": I: I 3 34 31 I37 INVENTOR s. Q Tm'eiw BY umm ATTORNEYS Dec. 9, 1958H. w. PARROTT ET AL BACK ADJUSTMENT FOR OFFICE CHAIRS 3 Sheets-Sheet 2Filed March 5, 1957 INVENTORS I I5 ll IHIIIIII ATTORNEYS 1958 H. w.PARROTT ETAL 2,863,497

' BACK ADJUSTMENT FOR OFFICE CHAIRS Filed March 5, 1957 I 5 Sheets-sheaf:s

v 43 4? ,44 K. i 23 INVENTORS W- w r ATTORNEYS 2,863,497 Patented Dec.9, 1958 2,863,497 BACK ADJUSTMENT Fon OFFICE CHAIRS Henry WheelerParrott, Shelton, and Sidney Albert Ericson, Bridgeport, Coun.,assignors to The Bassick Company, Bridgeport, Conn., a corporation ofConnecticut Application March 5, 1957, Serial No. 644,046 Claims. (Cl.155-157) This invention relates to back adjustments for ofiice chairsand particularly to those for chairs in which the back is pivotallymounted and vertically adjustable with respect to a non-tiltable seat.

In chairs of this type it has been the practice to equip a chair ironsupporting the seat with an assembly comprising a two-part bracket, onepart of which is a forward member pivoted in relation to theseat-supporting post and the other part of which is a member pivoted atits upper end to the first part and carrying a guide or trackway inwhich a chair-back-supporting member is adjustable vertically. Thisprovides for the vertical adjustment of the chair back by permitting thedesired raising or lowering of the part to which the chair back isfixed, and by swinging the rearward part of the two-part bracket theinclination of the chair back can be adjusted.

One of the principal objects of this invention is to provide improvedmeans whereby the member or element carrying the chair back andvertically adjustable can be easily and securely fixed at the desiredelevation.

Another object is to provide a clamping screw arrangement for thepurpose of clamping the back carrier in the desired position which willoperate without binding of the screw in its associated nut.

To these and other ends the invention consists in the novel features andcombinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. l is a side, elevation of an oflice the invention;

Fig. 2 is an elevation on a larger scale showing certain portions of thechair illustrated in Fig. 1; V

Fig. 3 is a top plan view with certain parts omitted showing a chairiron embodying the invention;

Fig. 4 is a section on line 4-4 of Fig. 3;

Fig. 5 is a section on line 5-5 of Fig. 4;

Fig. 6 is a section taken on the same section line as Fig. 4 but lookingin the opposite direction;

Fig, 7 is a section similar to Fig. 5 showing another position of theclamping screw appurtenant to the chair back;

Fig. 8 shows in detail the tiltable nut associated with the saidclamping screw; and

Fig. 9 is a section on line 9-9 of Fig. 6.

In the drawings there is shown by way of example an ofiice chair of theswivel type having a non-tiltable seat and a pivoted tiltable back whichis vertically adjustable. By referring to a tiltable back it is intendedto indicate that the back can be swung on a lower pivot to dilferentinclinations. In the chair illustrated, the base of the chair has anupwardly extended post carrying at its upper end a bracket or framewhich is secured to longitudinal bars to which the chair seat isaffixed. Extending rearwardly from thesaid frame or base member is atwopart element, the forward part of which is pivoted to said basemember or frame and under the control of a tensioning bolt or screw.Pivoted to the forward part pf this two-part bracket is a second partwhich is tiltable chair embodying bracket parts serves as a pivot.

2 in a vertical plane and which has at the rear part thereof an uprightguide or trackway in which is adjustable a channel-shaped elementcarrying the chair back. At the lower portion of this second bracketpart the same is operatively connected to an adjusting screw operable tovary inclination of the chair back. Also mounted upon the second bracketpart is a clamping screw arrangement involving a clamping screw or stemoperable from one side of the chair for clamping the back-carryingelement after the latter has been moved vertically to the desiredposition.

In the drawings, the upwardly extended supporting post is indicated at10, the bracket or frame at the upper end of this post at 11, thelongitudinal bars to which the seat is aflixed at 12, the forward partof the two-part element or bracket at 13, the tensioning screwconnection to part 13 at 14, the second or rear bracket part at 15, thechannel-shaped element carrying the chair back at 16, the adjustingscrew operable to vary inclination of the chair back at 17, and theclamping screw arrangement for clamping the back carrier element aftervertical adjustment at 18.

The bracket or frame 11 connected to the upper end of theseat-supporting post has parrallel horizontal side bars that arefastened in any suitable manner to the longitudinal bars 12 that areapplied in the usual manner to the lower face of the chair seat. Theforward bracket part 13 is extended between the rear end portions ofbars 12 and at 19 is a pivotai connection between the lower forward endportion of bracket part 13 and the frame 11. The part 13 is of generallyU-shaped cross section presenting a downwardly facing channel, and theupper wall of this member has an upstanding flange: 20 connected in theusual or any preferred manner with the tensioning screw 14, a coilspring 21 being interposed between the wheel-carrying nut 22 and a partof the frame 11.

At the rear of the bracket part 13 there is an upper pivotal connectionbetween this part and the rear bracket part 15 whereby the rear bracketpart is pivotally mounted so that the chair back may be placed atdifferent inclinations. The rear bracket part has side walls 23interconnected by a web 24 and this member is extended into the spacebetween rearwardly projecting wall portions of part 13, and a pivot pin25 extending across the bracket structure and passing throughoverlapping lugs of the two This pin 25 is rigid with the forwardbracket part, and the lugs of the rear part can turn relatively to thispin. Adjusting movement of the rear bracket part on its pivot can beproduced by rotation of an adjusting screw shank 26 locatedlongitudinally of the bracket parts 13, 15 and disposed horizontally atthe lower part of this bracket structure. This screw shank is rotatablysupported and held against longitudinal movement in a downwardlyextending flange 27 carried by part 1.3 at the lower portion thereof,said screw being engaged intermediate of its ends in a U-shaped nut 28engaged over the lower edge of the transverse wall of bracket part 15.This nut 28 is provided interiorly with a spring 29 arrangedin themanner shown in Fig. 6, and a clearance aperture 30 in part 15, throughwhich screw 26 passes, permits part 15 to swing relatively to the screw.The arrangement is such that when screw 26 is rotated in one directionthe lower part of the rear bracket member is swung rearwardly and whenthe screw is rotated in the opposite direction this part is swungforwardly. At the forward end of the screw 26 a universal coupling 31 isprovided, this being connected to a rotary adjusting stem 32 having anend wheel 33 accessible at one side of the chair seat. The rotaryelement or stem 32 is arranged at an acute angle to the longitudinalaxis of the chair iron and this rotary element has its inward endsupported by means such as a yoke 34 extending downwardly from a lowerwall provided interiorly of I bracket part 13.

The clamping screw arrangement 18, previously mentioned, is associatedwith the rear bracket part at an ele-' vation where the clamping screwis somewhat above the adjusting screw 17. This clamping screwarrangement comprises a threaded clamping screw or stem 35 extendedthrough an aperture 36 in one side wall of the bracket part and servingto clamp the channel element 16 in its adjusted position. The channelelement 16 is suitably mounted at the lower extremity of the chair backand, as shown herein, it comprises a relatively wide rear member 37 towhich is fixed a forward part 38. The side walls of part 15 present attheir outer faces V-shaped grooves so that there is provided on thismember a vertical guide or trackway,'and member 38 has inwardly bentflanges engaging these grooves. The threaded stem 35, which is arrangedat an acute angle to part 15, has an inner conical extremity that isadapted to enter the space between one of the V-shaped parts of thebracket and the flat forward face on the body of member 38. Forsupporting the stem 35 adjacent its inner extremity, a yoke 39 havingupper and lower prongs engaging the stem is rigidly fastened to theadjacent bracket wall.

t the opposite side of the bracket part, where the clearance opening 36is provided, the stem 35 has threaded engagement with a nut that issupported from the adjacent wall of the bracket in a manner such thatthe nut can move relatively to the bracket for purposes hereinaftermentioned. In the form herein shown, a nut 40, shown in detail in Fig.8, is provided, the same consisting of an interiorly threaded nut body41 rigidly fixed to an elongated plate structure 42 in such a mannerthat the nut body lies at an acute angle to the palne of the supportingplate. The supporting plate is an elongated plate having intermediate ofits ends a nut-body-carrying portion 4. 3 lying at an angle to the planein which the end portions of the end plate are disposed. The endportions of the plate are each provided with an integral lug 44 in thesame plane as the end portion of the plate. These lugs 44 serve formovably supporting the nut, said lugs being projected through slots 45of greater width than the thickness of lugs 44 to provide clearance forpivoting. After insertion into slots 45 the extremities of the lugs aredeformed by staking or swaging to present on the lugs enlargements bywhich the nut plate will be prevented from displacement from itssupporting wall. The nut plate extends in a vertical direction and thenut portion engaging the threaded stern can swing in a horizontal planefor the purpose of facilitating proper engagement of the stem extremitywith the angular space or socket presented respectively by the chairback carrier and the rear bracket part.

It will be noted that the plate 42 of the nut device is applied to thewall having the aperture 36, one end of the plate being above theaperture and the other end below it. When the stem 35 is withdrawn fromits cooperating angle or socket, as shown in Fig. 7, the stem can beswung laterally to a certain extent, as shown by the broken lines inFig. 7, the aperture 36 providing a clearance that permits this. Whenthe stem 35 is swung in this manner, its pivoting axis coincidesVertically with the pivotal mountings of the lugs 44 in the slots d5. Atthe outer ends of the lugs 44 the lugs are enlarged or provided withheads, as above described, and at the inner face of the bracket wall,shoulders 44a on the plate 42 abut the wall, the stem 35 when in thedisengaged position being freely swingable laterally to a certainextent. The conical end of the. stern, when the stem is moved inwardly,is free to engage one side or the other, or both, of the receiving anglefor the stem and on continued rotation of the stem the latter is free togo home in an accurately lined up position.

It is understood that the chair back carrier can be adjusted verticallythrough a range of substantial .extent and that it is very desirablethat this carrier be capable of secure clamping in all of its adjustedpositions. In prior height adjustments for chair backs where a clampingscrew or stem was intended to engage in an angle presented between thecarrier element and the bracket there has been serious malfunctioningand failure in firmly securing the carrier element due, for one reason,to the fact that in different height adjustments the receiving angle orsocket for the stem would be in different positions laterally of thebracket structure. This serious drawback is overcome by the structurepresently described. Another important advantage arises from the factthat where the nut supporting the threaded stem is rigidly fixed to thebracket there is likely to be serious binding of the stem in the nutbecause the stem is not accurately lined up with its receiving angle,and this defect is overcome by the herein described improvement.

The receiving angle referred to here is that presented by the verticallyelongated parts of the bracket wall and the back carrier having planarsurfaces at an acute angle to each other and adapted for engagement bythe conical extremity or nose portion of the clamping screw. in the formdescribed these surfaces are provided respectively on the forwardlyfacing channel portion of the back-supporting carrier or slide and bythe rearward lip portion at one side of the bracket.

Various modifications and detail changes may be made without departingfrom the principles of the invention and the scope of the claims.

What we claim is:

1. In a chair iron, a post-supported frame, a twopart bracket memberextending laterally from said frame having forward and rear bracketparts, the rear bracket part being tiltable in a vertical planerelatively to the forward bracket part, a back-supporting elementmovable vertically on said rear bracket part and forming in conjunctionWith one side of said rear bracket part an elongated acute angle orsocket formation, a rotary clamping screw extending through an aperturein a side wall of said rear bracket part and having a pointed extremityto engage in the angle or socket of said formation, said screw lying ina substantially horizontal plane and-extending outwardly of said bracketpart and the aperture through which said screw passes allowing clearancefor lateral movement of said screw, a nut in threaded engagement withsaid screw having a movable mounting within said bracket part to permitaccurate lining up of the screw with said angle or socket and a handstern disposed outwardly of said rear bracket part and fixed to saidscrew.

2. In a chair iron, a post-supported frame, a two-part bracket memberextending laterally from said frame having forward and rear bracketparts, the rear bracket part being swingable in a vertical planerelatively to the forward bracket part, the rear bracket part having achannel formation facing rearwardly with one of its side walls aperturedintermediate of the upper and lower ends of said bracket part, aback-supporting element movable vertically on said rear bracket part, arotary clamping screw disposed substantially horizontally and extendingfrom the exterior of said bracket part through the aperture of saidbracket part with clearance, said screw having within said bracket parta pointed end engageable in an acute angle provided between saidbacksupporting element and a wall of said rear bracket part, amountingnut for said screw located within said bracket part and having pivotalconnection with the latter at points above and below said aperturewhereby said screw can have a horizontal swinging movement to line it upwith said angle, and a hand stern disposed outwardly of said rearbracket part and fixed to said screw.

3. In a chair iron, the combination of a back-supporting member providedwith a forwardly facing channel uprightly disposed, a bracket part towhich said backsupporting member may be fixed in a number of verticaladjustments and formed as a rearwardly facing channel providing guidegrooves at the sides in which said back-supporting channel member isengaged, said bracket part having a side wall with an aperture thereinlocated forwardly of said back-supporting element, a nut membercomprising a threaded nut body and a plate at an angle to said nut body,said plate being mounted from said bracket part at points above andbelow said aperture in a manner such that said nut body can have alimited lateral swing, a clamping screw extending into said bracket partthrough and with clearance in said aperture and provided with threadsengaging those of said nut body, said screw having a pointed interiorextremity for engaging an angle or socket created between an innersurface of said back-supporting element and an inner surface of saidbracket part and a hand stem disposed outwardly of said rear bracketpart and fixed to said screw.

4. In a chair iron, a mounting nut for the clamping screw of achair-back-adjusting assembly, said nut having an interiorly threadednut body and rigid therewith a plate provided with opposite end portionsin a plane 'at an acute angle to the intermediate part of said plate,

said intermediate part carrying said body, and said end portions eachbeing provided with an integral lug adapted for projection through aslot in a supporting wall.

5. In a chair iron, a post-supported frame, a two-part bracket memberextending laterally from said frame having forward and rear bracketparts, the rear bracket part being swingable in a vertical planerelatively to the forward bracket part, the rear bracket part having achannel formation facing rearwardly with one of its side walls aperturedintermediate of the upper and lower ends of said bracket part, aback-supporting element movable vertically on said rear bracket part, arotary clamping screw disposed substantially horizontally and extendingfrom the exterior of said bracket part through the aperture of saidbracket part with clearance, said screw having within said bracket parta pointed end engageable in an acute angle provided between saidback-supporting element and a wall of said rear bracket part, and amounting nut for said screw located within said rear bracket part andhaving rigid therewith a plate provided with lugs loosely mounted inslots formed in said rear bracket part to establish pivotal connectionwith the latter at points above and below said aperture whereby saidscrew can have a horizontal swinging movement to line it up with saidangle.

References Cited in the file of this patent UNITED STATES PATENTS

